An awe-inspiring and panoramic investigation into the hidden world of the deep sea - a mysterious, unforgiving landscape whose secrets radically revise our understanding of life on earth. The deep sea is one of our planet's last frontiers. For most of human history, it has been a remote realm shrouded in obscurity. But here, where the light cannot reach, lies a strange, wonderful and breathtaking world, teeming with scientific marvels and lessons for the future of life on this planet. In The Dark Frontier, marine microbiologist and explorer Jeffrey Marlow plunges us into the ocean's depths and invites us to witness close-up encounters with its hidden brilliance. Translucent shrimp dance through sulphureous vents, crabs stretch twelve feet from claw to claw and the eerie chalk-white towers of the 'Lost City' loom. Immersive and illuminating, Marlow's journeys reveal alarming warning signs as well: we are irrevocably changing the deep sea before we have even had a chance to understand it. This expansive book offers crucial and surprising insights into the ways in which the twinned forces of exploration and exploitation have shaped our relationship with the ocean. It shows how life can thrive in even the most extreme conditions, and reveals critical links between the deep sea and life on land. The Dark Frontier expands our understanding of biological possibilities - and our responsibilities - on Earth and beyond.